1. Field of the Invention
The present invention relates to inspection apparatuses for inspecting a weld zone between a reactor pressure vessel and a structure inside a nuclear reactor. For example, the invention relates to an inspection apparatus for inspecting weld zones in a reactor pressure vessel, the inspection apparatus being capable of detecting a crack of a weld zone between a control rod drive housing and a reactor pressure vessel, which are located on the bottom of a boiling water reactor.
2. Description of the Related Art
In a pressure vessel of a nuclear reactor, it is necessary to check its soundness; in particular, weld zones and the like in the nuclear reactor need to be inspected. In most cases, visual inspection is performed periodically. If it is judged that further inspection is necessary as a result of the visual inspection, situational tests of the surface and inside of the material are carried out (the size of a crack is measured). Well known methods for the above inspection include ultrasonic testing and eddy current testing.
In addition, inspection areas often exist in narrow portions; therefore, as a method for improving such inspection efficiency, there is disclosed an inspection method in which a lower head of a pressure vessel of the nuclear reactor is inspected by use of a scanning cart that travels while adhering to the lower head (for example, refers to JP-A-6-11595).